@spec instance_id() :: String.t()

Returns the stable instance ID of this running node.

@spec recent_samples(
  String.t(),
  keyword()
) :: [map()]

Returns the most recent samples for monitor_id across the cluster.

Each sample is returned as a plain map with the following keys:

• :monitor_id - the monitor's string ID
• :instance_id - the instance ID (string/binary)
• :status - string representation of the health status (e.g., "up", "down", "degraded", "unknown")
• :latency_ms - nullable integer representing latency
• :status_code - nullable integer representing status code
• :metrics - map of numeric metrics
• :collected_at - UTC DateTime of the sample collection
• :synthetic - boolean indicating if this is a synthetic sample